Don't tell me you think Christ, God, needed to validate Himself? You believe that that is why Christ quoted the Septuagint?
You know, mm, I have for sometime now been suspicious that some Protestant theology is strangely Mohammedan. That's precisely how Mohammedan used both the OT and his own scriptural nonsense. The Mohammedans reduce Christ to the next to the greatest prophet. Do you reduce Him to a mere prophet who needs validation by scripture?. If you don't mean that, you should be more careful about what you say. Think it through.
Don't even go there....
The Catechism of the Catholic Church
841 The Church's relationship with the Muslims. "The plan of salvation also includes those who acknowledge the Creator, in the first place amongst whom are the Muslims; these profess to hold the faith of Abraham, and together with us they adore the one, merciful God, mankind's judge on the last day."330